"The desperation kicks in."

MANCHESTER, Iowa (AP) — As if hearing Marco Rubio's footsteps creeping up on him, Ted Cruz directed much of his final advertising against the Florida senator in the frenzied weekend prelude to the Iowa caucuses, feeding a Republican feud that turned increasingly bitter before voters have their first say in the 2016 presidential race.

Considered to be vying with frontrunner Donald Trump for Iowa victory Monday, Cruz denounced the next in line, according to polls, sharply challenging Rubio's conservative credentials on the airwaves while ignoring him face to face with Iowans. One ad said darkly of Rubio: "Tax hikes. Amnesty. The Republican Obama."

"The desperation kicks in," Rubio said in response to Cruz. "From my experience, when people start attacking you it's because you're doing something right."

On the Democratic side, Bernie Sanders implored Iowa supporters Saturday to get on their feet in two days and convert their monthslong infatuation with his upstart campaign against Hillary Clinton into actual votes. That call to action was echoed by Democratic and Republican hopefuls alike as they worked to motivate Iowans to attend the caucuses.

Trump, the showman of the Republican race and its frontrunner, made a dramatic entrance to a Dubuque rally as his jet flew low over a hangar half-filled by the waiting crowd and music played from the movie "Air Force One." There was more drama inside, as a small group of protesters interrupted him and Trump joined the crowd in chanting "USA" to drown out the discord.

He asked security to "get them out" but "don't hurt them."

Iowa offers only a small contingent of the delegates who will determine the nominees, but the game of expectations counts for far more than the electoral math in the state. Campaigns worked aggressively to set those expectations in their favor (meaning, lower them) for Iowa, next-up New Hampshire and beyond.

Asked whether Rubio could win or come second, his senior strategist Todd Harris laughingly responded with an obscenity and said the goal in Iowa is third, behind the flamboyant Trump and the highly organized Cruz.

"There's no question we are feeling some wind at our back," he told The Associated Press. But, he added, "It's very hard to compete with the greatest show on earth and the greatest ground game in Iowa history. So we feel very confident that what we need to do here is finish a strong third. I don't care what any of the polls say, Ted Cruz is going to win this caucus."

With that, he tried to set expectations so that if Rubio finishes better than third, it can be proclaimed a great performance and if Cruz doesn't win, it will be seen as a great failure.

In the last major preference poll before the caucuses, Trump had the support of 28 percent of likely caucus-goers, with Cruz at 23 percent and Rubio at 15 percent. The Iowa Poll, published by the Des Moines Register and Bloomberg, also found Clinton with 45 percent support to Sanders' 42 percent. The poll of 602 likely Republican caucus-goers and 602 likely Democratic caucus-goers was taken Tuesday to Friday and has a margin of error of plus or minus 4 percentage points.

[sharequote align="center"]"There's no question we are feeling some wind at our back."[/sharequote]

Pate said Cruz's campaign "misrepresents Iowa election law." There's "no such thing as an election violation related to frequency of voting," he said, and insinuating otherwise is "not in keeping in the spirit of the Iowa caucuses."

In Charles City, Iowa, a testy Sanders accused Clinton of misrepresenting his positions. He cited an ad from her campaign that says she would defend Planned Parenthood, "not attack it," and implies he has taken on the organization that offers contraceptive and abortion services. The ad, without naming him, also says she would "build on Obamacare," not start over, and stand up to the gun lobby, "not protect it," all swipes at the senator.

Sanders slammed the "idea that I am attacking Planned Parenthood when I have a 100 percent lifetime voting record for Planned Parenthood" and bristled at the implication that he's not for tougher gun laws.

"Let's debate those differences of opinion, but let's not go around distorting a record that I am very proud of," he said.

Clinton has worked assiduously to avoid a repeat of 2008, when then-Illinois Sen. Barack Obama scored a surprise win in Iowa, she dropped to third and her days as the prohibitive favorite for the nomination faded. She faced the prospect of escalating political heat from revelations Friday that the private email server she used when she was Obama's first secretary of state contained top-secret messages that should have remained within proper, secured channels.

That heat was coming from Republicans; Sanders earlier declared the email flap a nonissue in his mind.

But at a Sanders rally in Manchester, Iowa, Ruth Lewin, a retired grocery store clerk and child care provider, said the latest news about Clinton's emails reinforced why she will be caucusing for Sanders on Monday.

"It's a matter of honesty, integrity along with other issues I have about her," Lewin said. "When you get $600,000 for a speaking engagement, I mean that's more than I've made in my entire lifetime."

And Sanders? "I believe he's like we are," she said.

The Clinton and Sanders campaigns reached agreement to hold a debate in New Hampshire this coming week and three more in the spring, supplementing a light debate schedule that has favored weekend slots when fewer people watch TV. The tentative New Hampshire event is to be held Thursday, giving voters a chance to see the field debate before the state's primary Feb. 9.